Altra Industrial Motion, a US conglomerate that produces mechanical power transmission products, has bought the UK-based Hay Hall Group, whose members include Bibby Transmissions, Huco, Inertia Dynamics, Matrix International and Twiflex. The terms of the deal have not been disclosed. Hay Hall`s revenues last year were more than £37m.

The deal gives Altra more than 20 manufacturing sites around the world. The company already had eight plants in North America and another eight in China and Europe, including the Wichita Clutch plant in Bedford.

"Given the product synergies and the many combined strengths of the two companies, there are significant opportunities for our experienced management teams to capitalise upon identified growth initiatives and improve operational efficiencies," says Altra`s chief executive, Michael Hurt.

Massachusetts-based Altra was formed in 2004, when its largest investor, Genstar Capital, acquired the Colfax Power Transmission Group and merged it with the bearing-maker, Kilian Manufacturing.

Altra`s portfolio includes such well-known brands as Boston Gear, Warner Electric, Stieber, Wichita Clutch, Ameridrives Couplings, Marland Clutch and Nuttall Gear. Its sales in 2004 amounted to around $340m.

The companies that Altra has acquired include:

• Yorkshire-based Bibby Transmmissions, which makes couplings, torque limiters, torque sensors and backstops;

• Hertford-based Huco Dynatork, whose products include couplings, rod ends, brakes and clutches and, since acquiring Dynatork last year, air motors;

• US-based Inertia Dynamics, which produces electromagnetic and spring-loaded brakes and clutches;

• the Scottish clutches and couplings manufacturer, Matrix International; and

• the disc brake maker Twiflex, based in Twickenham, Middlesex.